1. Field of the Invention
The present invention generally relates to the field of integrated circuit design. More particularly, the present invention relates to the field of software tools for hierarchical physical design.
2. Related Art
The tremendous advances in technology have been fueled by improvements in integrated circuit design. In particular, integrated circuits have become smaller and more complex. Integrated circuit design engineers depend on electronic design automation (EDA) software tools to facilitate the design of integrated circuits.
Typically, the integrated circuit design process begins with a specification which describes the functionality of the integrated circuit and may include a variety of constraints. Then, during a logic design phase, the logical implementation of the integrated circuit is determined. Several operations are performed to obtain a logical representation of the integrated circuit. Generally, EDA software tools use register transfer logic (RTL) to represent the integrated circuit. However, additional EDA software tools may be used.
After completing the logic design phase, the integrated circuit undergoes a physical design phase. Typically, the output of the logic design phase is a netlist, which is then used in the physical design phase. Here, EDA software tools layout the integrated circuit to obtain a representation of the physical components in the integrated circuit, whereas the representation indicates the manner in which the integrated circuit will be implemented on a semiconductor chip. A variety of operations are performed on the layout of the integrated circuit.
At the end of the physical design phase, the representation of the semiconductor chip (in which the integrated circuit is implemented) is sent to a semiconductor manufacturing plant.
Typically, in the physical design phase, EDA software tools implement a flat physical design. For example, the components (standard cells, macrocells, etc.) of the integrated circuit are placed during a placement operation and are routed during a routing operation. However, as the integrated circuit becomes more complex, the EDA software tools struggle to perform the placement operation and the routing operation. In particular, the performance of the EDA software tools degrades since the EDA software tools have to manipulate very large files during the placement operation and the routing operation. Moreover, as the complexity of the integrated circuit increases, the time necessary to complete the physical design phase increases significantly.
Traditional hierarchical physical design has emerged as an alternative to the flat physical design. FIG. 1 illustrates the traditional hierarchical physical design 100. Here, the components of the integrated circuit are partitioned into a plurality of blocks 10-30. Each block 10-30 includes a plurality of pins 50, whereas each pin 50 represents a location where a signal can enter the block 10-30 or a location where a signal can exit the block 10-30. As illustrated in FIG. 1, the traditional hierarchical physical design 100 includes a channel 40. The channel 40 provides space in order to connect the pins 50 of the blocks 10-30 to one another via metal (not shown) or any other wiring material. The traditional hierarchical physical design 100 enables the placement operation and the routing operation (as well as other operations) for the blocks 10-30 to be performed in parallel with EDA software tools, reducing the time period of the physical design phase. Moreover, the performance of the EDA software tools is improved because the file for each block 10-30 is much smaller than the file for the entire integrated circuit of the flat physical design. More importantly, the EDA software tools are better suited to optimize each block 10-30 than to optimize the entire integrated circuit of the flat physical design. However, the traditional hierarchical physical design 100 generates wasted space in the channel 40 and generates wiring problems in the channel 40, such as congestion and crosstalk. Moreover, the traditional hierarchical physical design 100 places and routes components at a top-level (shown in FIG. 1) and a block-level (within each block 10-30), causing inefficiencies and causing problems with EDA software tools which are configured to operate with flat physical designs.